Stubborn Al-Sadd were up against it for long periods in Sunday's clash against Esperance of Tunisia, which was marred by fans of the African champions trying to get on the pitch at the end, with at least one succeeding.
Jorge Fossati's Al-Sadd, underdogs when they claimed the Asian crown in November, played classic counter-attacking football at Toyota Stadium, scoring with their first shot of the game and holding on for a hard-earned 2-1 victory.
Nobody will give the side from Doha a chance against Barcelona, who arrived in Japan fresh from the weekend's 3-1 drubbing of fierce rivals Real Madrid in the Bernabeu and are widely considered one of the best club sides ever.
"If we can have 15 or 16 players on the pitch we will have a good chance," Fossati said jokingly, when asked by AFP how his side could possibly beat the European champions on Thursday.
"One sports manufacturer says 'impossible is nothing,' and I want to believe that. Of course Barcelona are the best in the world, which we recognise, especially after the match against Real Madrid.
"But recently Getafe in Spain won against Barcelona (1-0). It sounds illogical and impossible. This is key. But as long as we are humble and maintain a strong spirit, we think it can happen."
Fossati, a former Qatar and Uruguay coach, said his unfancied side, who are taking part in the intercontinental Club World Cup for the first time, had made history.
"To play the best team in the world does not happen every day," he said. "We will try to enjoy this opportunity. For me, to play them in this game, is something very special that firstly you must enjoy.
"I want, in this moment, to enjoy this for a few hours—minimum. I want to enjoy this victory [against Esperance] now. A few hours from now I will start thinking about Barcelona."
Fossati, switching between English and Spanish at Sunday's post-match press conference, dismissed the notion that his dogged side were lucky in a game where Esperance enjoyed 57 per cent possession but were sloppy in front of goal.
"You need to make your own luck," he said. "For any player outside Spain, to play against Barcelona is a dream, but this match is going to be the most difficult challenge of our players' careers.
"I don't want to say any more about Barcelona."
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